Illuminating system for determining the topography of the cornea of an eye

Abstract

An illumination system for producing an illumination pattern for measuring the cornea of an eye and, in particular, for determining the topography thereof and in so doing facilitating distance-independent measurements. The illumination system according to the invention for determining the topography of the cornea of an eye includes an illumination unit and a unit for producing an illumination pattern, wherein the illumination unit includes a plurality of illumination modules. A lens array which produces a spatially distributed, collimated illumination pattern is used as a unit for producing an illumination pattern. The illumination system produces an illumination pattern, by which the topography of the cornea of an eye can be determined. Here, the illumination system is designed as a compact module, and so it can be easily combined with other measurement systems, without colliding with the beam paths thereof.

The invention claimed is: 
     
       1. An illumination system for determining the topography of the cornea of an eye, comprising:
 an illumination unit that is configured to provide illumination outside of a central region surrounding an optical axis thereby enabling telecentric axially symmetric detection and a unit that produces an illumination pattern; 
 wherein the illumination unit comprises a plurality of illumination modules, each of the plurality of illumination modules including a light source and at least one reflective or refractive optical element that images the light source toward the eye; and wherein the unit that produces the illumination pattern comprises a lens array which produces a spatially distributed, collimated illumination pattern outside of the central region. 
 
     
     
       2. The illumination system as claimed in  claim 1 , wherein the lens array comprises diverging lenses with a negative focal length. 
     
     
       3. The illumination system as claimed in  claim 1 , wherein the illumination unit comprises at least two of the illumination modules. 
     
     
       4. The illumination system as claimed in  claim 3 , wherein the illumination unit comprises at least four of the illumination modules. 
     
     
       5. The illumination system as claimed in  claim 3 , wherein the illumination unit comprises at least six of the illumination modules. 
     
     
       6. The illumination system as claimed in  claim 1 , wherein the illumination modules are arranged in such a way that the illumination light of each illumination module illuminates part of the unit for producing an illumination pattern. 
     
     
       7. The illumination system as claimed in  claim 1 , wherein each illumination module comprises at least one reflective or refractive optical element in addition to a light source to image the light source into the eye by way of the lens array. 
     
     
       8. The illumination system as claimed in  claim 1 , wherein each illumination module comprises an asphere as a refractive optical element in order to image the light source into the eye by way of the lens array. 
     
     
       9. The illumination system as claimed in  claim 1 , wherein each illumination module comprises a Fresnel lens as a refractive optical element to image the light source into the eye by way of the lens array. 
     
     
       10. An illumination system for determining the topography of the cornea of an eye, comprising:
 an illumination unit and a unit that produces an illumination pattern; 
 wherein the illumination unit comprises a plurality of illumination modules; and the unit for producing an illumination pattern comprises a lens array which produces a spatially distributed, collimated illumination pattern; 
 wherein each illumination module comprises an elliptical reflector as a reflective optical element to image the light source into the eye by way of the lens array, wherein the light source is situated at a first focus of the elliptical reflector and the eye is situated at a second focus of the elliptical reflector. 
 
     
     
       11. The illumination system as claimed in  claim 1 , wherein each of the illumination modules comprises a separate lens array. 
     
     
       12. The illumination system as claimed in  claim 1 , wherein the individual lenses of the lens array are arranged in a rectangular grid, a radially symmetric grid or a hexagonal grid on a spherical surface that is concentric with the eye. 
     
     
       13. The illumination system as claimed in  claim 1 , wherein the individual lenses of the lens array are arranged in a rectangular grid, a radially symmetric grid or a hexagonal grid on a plane surface. 
     
     
       14. The illumination system as claimed in  claim 12 , wherein the individual lenses of the lens array are aligned in such a way that the optical axes thereof intersect at a common center in the eye. 
     
     
       15. The illumination system is claimed in  claim 1 , wherein individual lenses of the lens array have a negative focal length which, in terms of magnitude, deviates by less than 15% from the distance between the cornea being illuminated and the lens array. 
     
     
       16. The illumination system is claimed in  claim 15 , wherein individual lenses of the lens array have a negative focal length which, in terms of magnitude, deviates by less than 10% from the distance between the cornea being illuminated and the lens array. 
     
     
       17. The illumination system is claimed in  claim 15 , wherein individual lenses of the lens array have a negative focal length which, in terms of magnitude, deviates by less than 5% from the distance between the cornea being illuminated and the lens array. 
     
     
       18. The illumination system as claimed in  claim 11 , wherein individual lenses are arranged on a side of the lens array facing away from the eye and a basic form of the lens array lies concentrically around the optical axis. 
     
     
       19. The illumination system as claimed in  claim 1 , wherein the lens array comprises an injection molded part.